• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.10A
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• pp.1065-1071
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• 2007

In this paper, in order to research spectrum usage efficiency in urban canyon environment at the microwave band, measurement and channel capacity analysis of multi-antenna technology is described. The measurement data obtained from 3 - 4 stories building area used and the propagation characteristics at the 3.7 and 8GHz band are analysed and compared. In case of $2{\times}2$ MIMO, channel capacities of 3.7 and 8 GHz band are calculated to 9.1 bps/Hz and S bps/Hz and in case of $4{\times}4$ MIMO, 21 bps/Hz and 12.5 bps/Hz respectively. Considering the coverage, SNR and channel capacity in urban environment, MIMO propagation characteristics of 3.7 GHz are more predominate than those of 8 GHz.

• 한국지구물리탐사학회:학술대회논문집
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• 2008.10a
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• pp.93-96
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• 2008

We analyze a precise seabed feature around the Hupo Bank by using Multi-beam echosounder. Multi-beam echosounder system can observe the topography undulation according to the navigation of the survey ship by shooting wide beam. It is possible to embody a precision seabed feature because it can be make high density of incompletion depth sounding between survey lines. Through this survey, there is the Hupo Bank which is 84 km long, 1-15 km wide, 5.3-160 m deep in the center, at the west is moat, at the east is scarp and submarine canyon. The top of the Hupo Bank is the Wangdol reef that has 5.3 m in depth of water at least. Moat in survey area is 30 m long, and 30-40 m wide and has a depressed channel. The gap of depth of water in scarp is approximately 60 m and shows a characteristic of cuttig plane. Submarine canyon is 3.5 - 13.5 km wide.

• Korean Journal of Remote Sensing
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• v.30 no.6
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• pp.755-767
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• 2014

In this study, detailed air flow characteristics in an urban areas were analyzed using GIS data and a Computational Fluid Dynamics (CFD) model. For this, a building construction algorithm optimized for Geographic Information System (GIS) data with a vector format (Los Angeles region imagery acquisition consortium 2 geographic information system, LARIAC2 GIS) was used. In the LARIAC2 GIS data, building vertices were expressed as latitude and longitude. Using the model buildings constructed by the algorithm as the surface boundary data in the CFD model, we performed numerical simulations for two building-congested areas in Los Angeles using inflow information provided by California Air Resources Board. Comparing with the inflow, there was a marked difference in wind speed and direction within the target areas, which was mainly caused by the secondarily induced local circulations such as street-canyon vortices, horse-shoe vortices, and recirculation zones. In street canyons parallel to the inflow direction, wind speed increased due to a channeling effect and, in street canyons perpendicular to the inflow direction, vertically well developed vortices were induced. In front of a building, a horse-shoe vortex was developed near the surface and, behind a building, a recirculation zone was developed. Near the surface in the areas where the secondarily induced local circulations, wind speed remarkably increased. Overall, wind direction little (largely) changed at the areas where wind speed largely increased (decreased).

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1996.10a
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• pp.172-175
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• 1996

외해로부터 해안선부근으로 이동하는 파랑은 해저협곡 및 대륙붕과 같은 해저지형의 변화, 방파제와 같은 해안구조물과의 상호간섭 및 파랑상호간의 비선형효과 등에 의해 굴절, 회절, 천수 및 쇄파 등과 같은 변화를 경험한다. 파랑변형의 원인이 되는 여러 변화 중에서 흥미 있고 연구할 가치가 있는 물리적 현상중의 하나는 Bragg 반사이다. (중략)

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2017.10a
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• pp.170-170
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• 2017

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2019.10a
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• pp.165-165
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• 2019

• Journal of the KSME
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• v.44 no.5
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• pp.34-40
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• 2004

2003년 11월, 현대 기아자동차가 모젠이라는 텔레매틱스 서비스를 선보이면서 본격적인 차량정보(car information)의 시대가 열렸다. 물론 이전에 대우자동차판매의 드림넷, SK-SKT의 엔트랙-네이트 드라이브, 삼성화재의 애니넷 등이 선 보였으나 회사의 경영 환경 및 시장 여건 등으로 캐즘(chasm : 깊은 협곡)현상을 넘기지 못하고 사업을 철수하거나 현상유지에 머무르고 있는 형편이다.(중략)

• Korean Journal of Ecology and Environment
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• v.50 no.1
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• pp.126-136
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• 2017

We describe characteristics of diversity and distribution of oak forests on the Daegok-cheon gorge of the Southeastern Korean Peninsula, the oldest prehistoric site, in view of a sort of food resources of acorns. The $Z{\ddot{u}}rich$-Montpellier School's method was adopted for field investigation on the oak dominant stands. A total of 20 phytosociological $relev\acute{e}s$ composed of 193 taxa were analyzed by syntaxonomy and ecological flora. The Daegok-cheon's oak forests occupied 36.9% ($513,374m^2$) of the surveyed area, and its 99% ($507,677m^2$) was Quercus variabilis and Q. serrata stands. Oak forests of the Daegok-cheon gorge are a kind of regional vegetation type characterizing by the high relative net contribution degree (r-NCD) of Platycarya strobilacea and Sapium japonicum, which are an edaphic type of the xerophilous and thermophilic oak forests. The region of the Daegok-cheon petroglyphs is defined as an ecoregion with rich acorn supply and abundant water resources, and the warmer environment, which attracts prehistoric man.

• Economic and Environmental Geology
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• v.57 no.4
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• pp.449-471
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• 2024

We investigated the radiometric ages and petrological characteristics of basaltic rocks with columnar joints, basalt gorge, pillow lava, and mantle xenolith, from the geoheritages designated as Natural Monuments of Korea in recognition of their historical, academic, and scenic excellence. A total of 7 Natural Monuments were selected. They are 'Basalt gorge along Daegyocheon Stream of Hantangang River', 'Basalt gorge and Bidulginangpokpo Falls of Hantangang River, Pocheon', 'Pillow lava in Auraji, Pocheon' distributed along the Chugaryeong Fault System, 'Peridotite xenolith-bearing basalt in Jinchon-ri Baengnyeongdo Island, Ongjin', 'Columnar joint in Daljeon-ri, Pohang', 'Columnar joint in Yangnam, Gyeongju', and 'Columnar joint along Jungmun and Daepo Coasts, Jeju'. They ranged in age from the Cenozoic Neogene Miocene to the Quarternary Pleistocene. Based on the composition of major elements, Hantangang Basalt corresponded to trachybasalt, Daljeon Basalt to phonotephrite, Eoil Basalt to sub-alkaline basalt, and Daepodong Basalt to alkaline basalt. And in the composition of trace and rare earth elements, only Eoil Basalt showed the characteristics of arc basalt, while the others showed the characteristics of oceanic island basalt.

• Tribology and Lubricants
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• v.12 no.2
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• pp.41-47
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• 1996

고속에서 작동하는 공기동압 스핀들을 개발하기 위해 축방향 하중을 포함하여 설계와 관련된 문제들을 살펴보았다. 협곡이론에 근거한 지배방정식을 사용하였고, 차분법을 사용하여 해석하였다. 설계인자인 홈의 형상, 홈의 각도, 회전수, 그리고 편심량 등을 사용하여 축방향과 원주방향의 압력분포를 수치해석적으로 구하였다.